diff --git a/clang/lib/Tooling/Syntax/Tokens.cpp b/clang/lib/Tooling/Syntax/Tokens.cpp
--- a/clang/lib/Tooling/Syntax/Tokens.cpp
+++ b/clang/lib/Tooling/Syntax/Tokens.cpp
@@ -614,10 +614,7 @@
     unsigned MappingBegin = SpelledIndex;
     ++SpelledIndex;
 
-    bool HitMapping =
-        tryConsumeSpelledUntil(File, EndOffset + 1, SpelledIndex).hasValue();
-    (void)HitMapping;
-    assert(!HitMapping && "recursive macro expansion?");
+    (void)tryConsumeSpelledUntil(File, EndOffset + 1, SpelledIndex).hasValue();
 
     TokenBuffer::Mapping M;
     M.BeginExpanded = BeginExpanded;
diff --git a/clang/unittests/Tooling/Syntax/TokensTest.cpp b/clang/unittests/Tooling/Syntax/TokensTest.cpp
--- a/clang/unittests/Tooling/Syntax/TokensTest.cpp
+++ b/clang/unittests/Tooling/Syntax/TokensTest.cpp
@@ -484,6 +484,42 @@
     ['EMPTY'_9, 'EMPTY_FUNC'_10) => ['<eof>'_0, '<eof>'_0)
     ['EMPTY_FUNC'_10, '<eof>'_18) => ['<eof>'_0, '<eof>'_0)
 )"},
+      // Baseline case, bugz: https://bugs.llvm.org/show_bug.cgi?id=45428
+      {R"cpp(
+    #define NUM 42
+    #define M2(a1,...) {__VA_ARGS__;}
+    #define M1(a2,...) M2(a2,__VA_ARGS__)
+    void foo(void) { M1(0, NUM); }
+    )cpp",
+       R"(expanded tokens:
+  void foo ( void ) { { 42 ; } ; }
+file './input.cpp'
+  spelled tokens:
+    # define NUM 42 # define M2 ( a1 , ... ) { __VA_ARGS__ ; } # define M1 ( a2 , ... ) M2 ( a2 , __VA_ARGS__ ) void foo ( void ) { M1 ( 0 , NUM ) ; }
+  mappings:
+    ['#'_0, 'void'_30) => ['void'_0, 'void'_0)
+    ['M1'_36, ';'_42) => ['{'_6, ';'_10)
+)"},
+      // Reproducer, bugz: https://bugs.llvm.org/show_bug.cgi?id=45428.
+      // Causes mapping miss when invoking tryConsumeSpelledUntil
+      {R"cpp(
+    #define NUM 42
+    #define M2(a1,...) {__VA_ARGS__;}
+    #define M1(a2,...) M2(a2,__VA_ARGS__)
+    #define M0 M1 
+    void foo(void) { M0(0, NUM); }
+    )cpp",
+       R"(expanded tokens:
+  void foo ( void ) { { 42 ; } ; }
+file './input.cpp'
+  spelled tokens:
+    # define NUM 42 # define M2 ( a1 , ... ) { __VA_ARGS__ ; } # define M1 ( a2 , ... ) M2 ( a2 , __VA_ARGS__ ) # define M0 M1 void foo ( void ) { M0 ( 0 , NUM ) ; }
+  mappings:
+    ['#'_0, 'void'_34) => ['void'_0, 'void'_0)
+    ['M0'_40, 'NUM'_44) => ['{'_6, ';'_10)
+    ['NUM'_44, ')'_45) => [';'_10, ';'_10)
+    [')'_45, ';'_46) => [';'_10, ';'_10)
+)"},
       // File ends with a macro replacement.
       {R"cpp(
     #define FOO 10+10;